Question

In express, when I use routing middleware, is it OK to append to the request object? Or is it a bad pattern? Alternatives? Thanks.

app.get('/', getLayout, function(req, res){
    if(req.layout == 'simple') ...render simple layout...
    else ...render full layout...
});

where

getLayout = function(req, res, next){
    req.layout = (req.params.blah == 'blah') ? 'layout_simple' : 'layout_full';
    next();
}

Answer 1

I don’t see why you shouldn’t.

I do it a lot.

I am under the impression this is what middleware typically does.

From the express docs:
https://expressjs.com/en/guide/writing-middleware.html

They set req.user in their middleware as the current user.